Method of manufacturing superconductive coil by explosive compaction

Abstract

A method of manufacturing a superconductive coil by means of explosive compaction. A wire formed of silver having a superconductive oxide powder charged therein is formed into a coil. The coil is placed within a cylindrical vessel, into which a pressure medium is charged. Explosive compaction is carried out to cause the compaction of the coil through the cylindrical vessel and the pressure medium and hence densify the coil. The compacted coil is heat-treated in an air or oxygen atmosphere. The resulting superconductive coil possesses high critical electric current density. Advantageously, the coil is mounted on a mandrel axially extending therethrough, and placed together with the mandrel into the cylindrical vessel, before explosive compaction.

What is claimed is: 
     
       1. In a method of manufacturing a superconductive coil by means of explosive compaction by forming into a coil a tubular wire formed of silver having a superconductive oxide powder charged therein, subjecting said coil to explosive compaction to densify said coil, and heat-treating said coil thus densified in an air or oxygen atmosphere, the improvement comprising the steps of:   (1) placing said coil within a cylindrical vessel and charging a pressure medium comprising a non-compacting powder which is not solidified by said explosive compaction or a fluid, into said cylindrical vessel; and   (2) carrying out said explosive compaction to cause compaction of said coil by the action of a shock wave traveling through said cylindrical vessel and said pressure medium and hence densify said coil.   
     
     
       2. The method as claimed in claim 1, wherein said coil is placed within said cylindrical vessel at a central location thereof. 
     
     
       3. The method as claimed in claim 1, wherein said pressure medium comprises said non-compacting powder and said non-compacting powder has a mean particle size of 1 to 1000 microns. 
     
     
       4. The method as claimed in claim 1, wherein said pressure medium comprises said fluid. 
     
     
       5. The method as claimed in claim 1, wherein said superconductive oxide powder is a powder of an oxide having a perovskite structure formed of at least one of rare earth elements and yttrium, at least one of alkali earth metals, copper, and oxygen. 
     
     
       6. The method as claimed in claim 1, wherein said superconductive oxide powder is a powder of Bi-Ca-Sr-Cu-O oxide. 
     
     
       7. The method as claimed in claim 1, wherein said superconductive oxide powder is a powder of Tl-Ca-ba-Cu-O oxide. 
     
     
       8. The method as claimed in claim 1, wherein said cylindrical vessel is formed of one material selected from the group consisting of metal, an alloy thereof, synthetic resin, glass, ceramic, and cardboard. 
     
     
       9. In a method of manufacturing a superconductive coil by means of explosive compaction by forming into a coil a tubular wire formed of silver having a superconductive oxide powder charged therein, carrying out explosive compaction to densify said coil, and heat-treating said coil thus densified in an air of oxygen atmosphere, the improvement comprising the steps of:   (1) mounting said coil on a mandrel axially extending therethrough, said mandrel having a smaller diameter than an inner diameter of said coil;   (2) placing said coil mounted on said mandrel within a cylindrical vessel and charging a pressure medium comprising a non-compacting powder which is not solidified by said explosive compaction or a fluid, into said cylindrical vessel; and   (3) carrying out said explosive compaction to cause compaction of said coil by the action of a shock wave traveling through said cylindrical vessel, said pressure medium, and said mandrel, and hence densify said coil.   
     
     
       10. The method as claimed in claim 9, wherein said coil is placed within said cylindrical vessel such that said coil has an axis thereof in alignment with axes of said mandrel and said vessel. 
     
     
       11. The method as claimed in claim 9, wherein said pressure medium comprises said non-compacting powder and said non-compacting powder has a mean particle size of 1 to 1000 microns. 
     
     
       12. The method as claimed in claim 9 wherein said pressure medium comprises said fluid. 
     
     
       13. The method as claimed in claim 9, wherein said mandrel is formed of metal. 
     
     
       14. The method as claimed in claim 9, wherein said mandrel is formed of ceramic. 
     
     
       15. The method as claimed in claim 9, wherein said superconductive oxide powder is a powder of an oxide having a perovskite structure formed of at least one of rare earth elements and yttrium, at least one of alkali earth metals, copper, and oxygen. 
     
     
       16. The method as claimed in claim 9, wherein said superconductive oxide powder is a powder of Bi-Ca-Sr-Cu-O oxide. 
     
     
       17. The method as claimed in claim 9, wherein said superconductive oxide powder is a powder of Tl-Ca-Ba-Cu-O oxide. 
     
     
       18. The method as claimed in claim 9, wherein said cylindrical vessel is formed of one material selected from the group consisting of metal, an alloy thereof, synthetic resin, glass, ceramic, and cardboard.